I've apparently solved the issue, though I'm not quite sure how, because I did nothing different this time around. I redownloaded everything, decrapped it as I had before, had to go through the launcher, but now my custom patterns stay when I put a dishwasher in the store counters. It's still not perfect, when I use the eyedropper tool to copy a counter I've customized, the copy has the default pattern, but I can at least change it and have my customizations stay.  I haven't tried placing a corner cabinet yet, but I can live with this.

Yes I did.  I even deleted my saves and tried a fresh neighborhood, but still no dice.

I really hate having to register and ask a question, because I've solved most of the issues I've had using the search function, and I doubly hate having to necrobump, especially a thread where the issue is apparently resolved, but I'm having this problem even with decrappifying. 

I've decrapped the sims3pack files, or whatever the original files are called, and, when that didn't work, I decrapped the package files that are extracted from Delphy's Multi-Installer, but that too produced no results.  I even got so desperate I tried installing my decrappified sims3pack via the launcher, and when that didn't work, decrappified the packages the Launcher extracted.  Each time I retry, I delete all the cache files in the Documents/EA/Sims3. I'm using the latest version of s3rc.

I'm not sure if I'm decrappifying wrong, if I'm missing some other thread on here with a solution to the problem, or if these store objects are just irredeemably broken. Any help would be appreciated.